A wide range of medical treatments are known that utilize “endoluminal prostheses.” As used herein, endoluminal prostheses are intended to mean medical devices that are adapted for temporary or permanent implantation within a body lumen, including both naturally occurring and artificially made lumens. Examples of lumens in which endoluminal prostheses may be implanted include, without limitation: arteries, such as those located within the arteries, veins gastrointestinal tract, biliary tract, urethra, trachea, hepatic and cerebral shunts, and fallopian tubes.
Stent prostheses are known for implantation within a body lumen for providing artificial radial support to the wall tissue that defines the body lumen. To provide radial support to a blood vessel, such as one that has been widened by a percutaneous transluminal coronary angioplasty, commonly referred to as “angioplasty,” “PTA” or “PTCA”, a stent may be implanted in conjunction with the procedure. Under this procedure, the stent may be collapsed to an insertion diameter and inserted into the vasculature at a site remote from the diseased vessel. The stent may then be delivered to the desired treatment site within the affected vessel and deployed, by self-expansion or radial expansion, to its desired diameter for treatment.
Recently, flexible prosthetic valves supported by stent structures that can be delivered percutaneously using a catheter-based delivery system have been developed for heart and venous valve replacement. These prosthetic valves may include either self-expanding or balloon-expandable stent structures with valve leaflets attached to the interior of the stent structure. The prosthetic valve can be reduced in diameter, by crimping onto a balloon catheter or by being contained within a sheath component of a delivery catheter, and advanced through the venous or arterial vasculature. Once the prosthetic valve is positioned at the treatment site, for instance within an incompetent native valve, the stent structure may be expanded to hold the prosthetic valve firmly in place. One embodiment of a stented prosthetic valve is disclosed in U.S. Pat. No. 5,957,949 to Leonhardt et al. entitled “Percutaneous Placement Valve Stent”, which is incorporated by reference herein in its entirety.
Due to the size of replacement heart valves, percutaneous delivery of a prosthetic heart valve necessitates a low profile delivery system in order to access the heart via the vasculature without performing a more invasive procedure. Some current delivery systems for delivering and deploying balloon-expandable prosthetic heart valves, for instance, are as large as 24 F, which is too large for femoral access in many patients, especially in female and pediatric subjects. Such delivery systems often include a large diameter balloon for expanding and deploying the balloon-expandable prosthetic heart valve, which undesirably adds significant bulk to the crossing profile of the delivery system.
When a prosthetic valve is deployed at the treatment site, a fundamental concern is that the prosthesis be deployed as precisely as possible, particularly where the prosthetic valve is used to replace an insufficient or incompetent heart valve. However, accurate positioning of the prosthetic valve may be difficult due to complexities in the anatomy as well as other factors, and an initial deployment of the prosthetic valve may result in a less than optimal positioning or, even worse, an inoperable positioning. As such it would be desirable that the prosthetic valve delivery system accommodate some re-positioning of the prosthetic valve prior to final deployment without adding to the crossing profile of the system.
Another concern when percutaneously delivering a prosthetic valve to replace a heart valve is whether deployment of the replacement heart valve can be accomplished without, or with minimal, blood stoppage during the interventional procedure. Minimizing or eliminating blood stoppage during an interventional procedure is desirable as it avoids complications associated with stopping the heart during the procedure.
Therefore, it would be desirable to have a low profile prosthetic valve delivery system that allows re-positioning of the prosthetic valve, if necessary, and that minimizes or eliminates blood flow stoppage during the valve replacement procedure.